Voxel-wise prostate cell density prediction using multiparametric magnetic resonance imaging and machine learning

Abstract

Background: There are currently no methods to estimate cell density in the prostate. This study aimed to develop predictive models to estimate prostate cell density from multiparametric magnetic resonance imaging (mpMRI) data at a voxel level using machine learning techniques.

Material and methods: In vivo mpMRI data were collected from 30 patients before radical prostatectomy. Sequences included T2-weighted imaging, diffusion-weighted imaging and dynamic contrast-enhanced imaging. Ground truth cell density maps were computed from histology and co-registered with mpMRI. Feature extraction and selection were performed on mpMRI data. Final models were fitted using three regression algorithms including multivariate adaptive regression spline (MARS), polynomial regression (PR) and generalised additive model (GAM). Model parameters were optimised using leave-one-out cross-validation on the training data and model performance was evaluated on test data using root mean square error (RMSE) measurements.

Results: Predictive models to estimate voxel-wise prostate cell density were successfully trained and tested using the three algorithms. The best model (GAM) achieved a RMSE of 1.06 (± 0.06) × 10³ cells/mm² and a relative deviation of 13.3 ± 0.8%.

Conclusion: Prostate cell density can be quantitatively estimated non-invasively from mpMRI data using high-quality co-registered data at a voxel level. These cell density predictions could be used for tissue classification, treatment response evaluation and personalised radiotherapy.

Graphical Abstract

Acknowledgments

The authors would like to thank Courtney Savill and Lauren Caspersz for their contribution in specimen preparation and MRI acquisition.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by NHMRC grant 1126955, PdCCRS grant 628592 with funding partners: Prostate Cancer Foundation of Australia, and the Radiation Oncology Section of the Australian Government of Health and Aging and Cancer Australia. Yu Sun is funded by the Melbourne International Research Scholarship, the Movember Young Investigator Grant through Prostate Cancer Foundation of Australia (PCFA) and Cancer Therapeutics Top-up Funding. Dr Reynolds is funded by the Movember Young Investigator Grant through PCFA’s Research Program.